If you need to be able to rotate the eyes separately or want to build in this functionality for the futire, you will need to add some more bones to the biped.
Click the systems icon under the create tab, then 'Bones' and enter the highlighted settings. Don't worry about the 'fins' settings - they are just to your preference.
Make sure you are in the left viewport by pressing 'l' and single-click. Drag the mouse and you will see the bone appear. Make it a decent size (about the depth of the head, and then single-click again. You will see another bone linked to the first. We don't want this one, so now press escape, and a little 'nub' will be created. Select this and delete it so we have one single bone.
However, in order to be able to attach the bones to the mesh via the 'physique' modifier in the next step, we have to create a 'bone end' for the eye-bones.
To do this, make sure that the eye-bone is selected, then go to Character -> Bone Tools. The following dialogue will pop up. Click 'Create End'.
The bone will now look like the image above with the end nub, but there is an important distinction between the two.
When you are happy with this eye-bone complete with it's end, make a copy of it for the other eye, and rename them to something sensible.
